Level



Aug. 9, 1960 C. J. MISTRETTA LEVEL Filed May 10, 1956 Wwe United States This invention relates to levels. More particularly, this invention relates to those levels which may be used to measure the angle of slopes relative to a level plane or to a vertical plane.

Present levels are limited in use in that they may be used only to determine one or at best a few preset angles.

It is an object of this invention to provide an inexpensive lightweight level which may be used in measuring or setting any angle to the horizontal or perpendicular.

It is a further object of this invention to provide a compact level which is of simple construction and economical to produce.

A further object of this invention is to provide a level having no moving parts yet capable of measuring accurately any angle to the perpendicular or horizontal.

Yet another object of this invention is to provide a level easily readable at any angle.

These and other objects and advantages of this invention will be apparent from the following description and claims.

In the accompanying drawings which illustrate by way of example various embodiments of this invention:

Fig. l is a front elevation view of the `level showing the arrangement of the various bubble chambers and indexes;

Fig. 2 is a bottom view of Fig. l with a portion of the sealing strip removed;

Fig. 3 is a sectional View along line 3-3 of Fig. l;

Fig. 4 is a sectional view along lines 4-4 of Fig. l;

Fig. 5 is an exploded perspective view of the level showing an alternative method of construction;

Fig. 6 shows schematically how an arc may be divided into sections of equal vertical height and the geometrical disposition of the resulting arc segments along a common base line to proved vertical and horizontal condensation.

The level as shown in Figs. l through 4 comprises a front frame member 10, arear frame member 11 and a sealing strip 12 which may be constructed of a transparent plastic material. Each of the frame members is a solid molding consisting of a web or rear wall 13 with end walls 14, upper wall l5 and lower wall 16 cooperating to form a shallow tray. The outer surface of the web or rear` wall 13 has molded"therein arcuate grooves or recesses 20, 21, 22, 23, 24, 25 arid- 26. The grooves 20, 21, 22, 24, 25 and 26 are closed at their upper end by upper wall 15. Groove 23 has both ends opening at the lower wall 16. The lower portions 27 of the grooves 20, 21, 22, 23, 24, 25 and 26 open through lower wall 16 as best shown in Figs. l and 2. Closure of the upper ends of grooves 26, 21, 22, 24, 25 and 26 may alternatively be accomplished by terminating the grooves within web or rear wall 13. ilndex marks as at 30 and 31 together with suitable numerical indications as at 32 and 33 may be molded in the frame members. The lower wall 16 of each frame member includes a downwardly extending lip or ange 34.

The grooves 20 through 26 are so arranged in each frame member that when the rear walls 13 of the two arent fice frame members are secured together by any suitable means such as adhesive, screws, bolt-s or rivets, the grooves or recesses therein cooperate to form arcuate bubble chambers 35, 36, 37, 38, 39, 40 and 41 which are arranged in definite relation to the lower edge of the lower wall 16 in a manner providing a predetermined arc. In the drawings this arc is illustrated as 180. Each tube is completely lled with a suitable spirit fluid except for a small space allowed for an air bubble 45 of uniform size.

When the frame members are secured together as noted above, lips or flanges 34 and the lower walls 16 of the frame members 10 and 11 cooperate to form a slot 46 having the openings of the lower ends of the bubble chambers 35, 36, 37, 38, 39, 40 and 41 in its upper surface. After the lling ofthe bubble chambers as noted above, sealing strip 12 is lsecured by adhesive or the like in slot 46 thus sealing the lower ends of the bubble chambers.

An example method of determining the arc segments which ldene the length and linear contour of the acuate grooves to be used in the rear wall or web 13 of the frame members 10 and 11 is shown at Fig. 6. Quarter circle 60, having one determining radius 61 parallel to lower walt 16 of the frame members, is divided into consecutive arc segments A, B, C and D by chords 62, 63 and 64 which are mutually parallel to the radius 61 and the wall 16. These parallel chords are constructed to divide the vertical height of the quarter circle into consecutive arc segments having substantially equal vertical heights, here shown as 1A of the radius of the original quarter circle. The arcs A, B, C and D thus determined are then vertically disposed in horizontal arrangement with a common base line here shown as being common to extended chord 64, and thus fall within an area having a vertical dimension substantially equal to the spacing origi nally used between the dissecting chords. Thus, it is seen that in 1/2 of the level a full 90 arc comprised of the arc segments A, B, C and D is now disposed within a vertical dimension equal to approximately 1A of the radius of the original arc. It can readily be seen that any degree of vertical condensation may be obtained within the spirit of this disclosure by using various numbers of equally spaced and mutually parallel chords.

Horizontal compaction of the segments A, B, C and D, resulting in reduced overall length of the level, is obtained by moving each of the arc segments as far as possible toward the center of the level maintaining only sufficient spacing betwen each of the arc segments to allow for the horizontal dimension of the bubble chambers and the thickness of the chamber walls. As shown in Fig. 6, this horizontal compaction of the segments may be obtained by moving the geometrical center of each segment away from the perpendicular radius 68 of the original quarter circle as at 65, 66 and 67.

ln the alternative method of construction shown in Fig. 5,`the level is comprised of frame members and 81, separating plate 82` and arcuate tubes 85, 86, 87, 88, 89, and 91. The frame members 80 and 81 are constructed in the same manner as the members 10 and 11 above with the exception that lips or ilanges 34 are eliminated and the arcuate grooves do not extend through the lower wall of the frame members. In this construction, transparent, sealed, thin-wall arcuate tubes 85, 86, 87, 88, 89, 90 and 91 containing spirit fluid and having individual bubbles are held in proper position between the transparent plastic sides 80 and 81. These tubes may be somewhat exible to permit them to conform readily to the curvature of the grooves in the coniining members.'

A. separating plate 82 is inserted between members 80 and 81 and has arcuate slots 100, 101, 102, 103, 104, and 106 therein conforming in shape to the arcuate 3 grooves in members 80 and 81 but of a size slightly larger than the outside dimensions of the bubble tubes. In this construction the bubble tubes fit within the plate 82 and are confined by the grooves in members 80 and 81. The

member 82 is preferably made of plastic but may `also beV madeof paper, cardboard or any other suitable material and may have the indicia, indexing numbers and manufacturers Vdata printed thereon in preference to having such information molded on the members A80` and 81.

AIt is obvious that separating plate 82. may be eliminated iff theA grooves in frame members 80 and 81 are lsuiiiciently enlarged to completely accept the bubbletubes. Necessary indicia may be molded in or printed on the frame members. i

After insertion of the tubes in theplate `82, `the plate and the members 80 an:d 81 aresecured together with screwsV i110, 111 and 112jwhieh cooperate with screw holes 113,114 and 115. VWhile a method of securing with screws `is shown, it is understood that the securing maybe accomplished by any suitable means such as bolts, adhesives or rivets without `departing fromY theV spirit of the invention. i Y Y It is to be noted that while plastic has been specified as the preferred material in making this invention, it is understood that lany suitable, stable material suchfas a metal or wood could be used in makingthe various members with only the tubes or grooves forming the ybubble chambers being of a transparent material.

While the accompanying drawings show the indexing numbers inscribed to read the angle from the horizontal, any change of -this numbering such as: reversing the numerical arrangement to read the angle from the vertical; indexing both the `angle value shown and its complenientary angle toV facilitate reading'angles from the horizontal `as well as from the vertical; or indexing the complementary values on the front -and back frame membersmay be accomplished yWithout departing from the spirit of the invention.

It is understood that the outline Icontour of theV ends and upper walls of the disclosure are not critical and may be varied without departing from this disclosure.

vIt -is Ato be-noted that each of the arcuate tubes or bubble'chambers may be extended to allow for overlapF ping arc coverage in the areas of division between successive arcs.

While the-invention hasjbeen described in connection with'diierent embodiments thereof, it will be understood that it is capable offurther modification, and this application is intended to cover' any variations,ruses, or adaptations of the inventionfollowing, in general, f the principles ofthe invention and including such departures from. the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be `applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim-is:

Y 1. Alevel comprising secured front and back frame membens, each of said frame members having a plurality of arcuate grooves therein, said grooves being arcuate in lmannerdescribed 'by' consecutive arcs of a semi-circle, said grooves being vof substantially equal vertical height 'chords into a plurality of substantially equal portions, a

slotted separating index plate'secured between said-front and back lfratrie members and lcoextensive therewith, said slots in said plate conforming with said arcuate grooves, transparent tubes containing spirit uid and a bubble, said tubes conforming substantially to said arcuate grooves in said frame members, and said tubes located in the respective cooperating grooves of said frame members and said slots of said index plate.

2. A level `having multiple transparent bubble chambers therein and astraight horizontal lower side, said bubble chambers defining consecutive overlapping -arcs of a circle and havingthe general configuration, substantially the same vertical dimensions and the same relative angular orientation as the arcs ofthe quarter of said circle defined by a first radius of said circle parallel to said lower side andianother radius of. said circle perpendicular to said horizontal side and disposed on theupper side of said rst radius determined bymutually parallel lines parallel to said Yfirst radius of said circle and dividing said other radius ofsaid circle into a plurality of substantially equal portions, said bubble chambers, exclusive of overlap, collectively defining an arc substantially greater than said bubble Vchambers vertically disposed in v'horizontal alignment in said level, one of said bubble chambers intersecting a line parallel to said lower side of said level at a right angleand second of said bubble chambers intersecting a line perpendicular to said lower sideof said level at a rightV angle, wherein said, bubble chambers collectively comprise fan arc including `a right angle defined by lines parallel and vertical to said. lo-vver side and extending substantially beyond each of said lines, vsaid bubble chambers being transparent throughout their delined length, two transparent frame members, said frame Ymembers being a front frame member and a back frame mem-ber, each of said frame members comprising a rear wall, Yside walls, an upper wall and a lower Wall, saidl rear wall having grooves'therein, said grooves being closed :at the upper. end by 'said upper Wall and extending through said lower wall, said grooves configured in the manner of said bubble chambers, said front frame member and said back frame member being connected so that said grooves in the rear walls of the two frame members cooperate to form said bubble chambers, said rear walls being secured together by a suitable sealing means. and a sealing strip sealing the lower end ofsaidbubble chambers.

Spirit LeveLfrom April 1945 Modern Plastics, pp. 122 and 123.

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